NEW YORK (TheStreet) -- Sprint (S) spiked Tuesday after T-Mobile (TMUS) amended its Simple Starter plan one week after Sprint announced its new pricing plan.

T-Mobile quadrupled the data capacity for its Simple Starter plan. The new plan offers unlimited talk and text and 2GB of LTE data for $45, just $5 more than the current price point. The new plan will be available as of Wednesday, Sep 3.

Last week, Sprint unveiled its new pricing plan, which it said essentially doubles the amount of data customers can receive at a price that matches or beats competitors.

The third-largest U.S. wireless carrier announced a new family plan could include up to 10 lines with 20GB of shared data and unlimited talk and text for $100 a month as part of the promotion that lasts through 2015. The new pricing also contains a promotion for an additional 2GB per line for up to 10 lines through 2015.

T-Mobile's announcement could start a price war with Sprint after the two companies were embroiled in merger talks for months.